Screen with slot-and-circular opening-pattern for hammer mills



Nov. l1, 1952 E. L. COLE 2,617,600

SCREEN WITH SLOT-AND-CIRCULAR OPENING-PATTERN FOR HAMMER MILLS FiledJul;r 26, 1950 mm om oo m0?) omcsoooo GO Cro-mm co0 o0 m oo o o o oomoooczwmooommoo oo O oomoomooo oo moooczmooomooo oo Gxxmoqpmmoeexmzsepooo \H l o o O INVENToR. 0308( 8080 Ll/df? l. Co/e O O O O W7. j. BY WMMPatented Nov. 11,.-1952 t UNITED 'if-snr orifice Y 2,617,6tt y y nsl'ior-ANn-ornorimn oBEN. INGPTTERN FOR IiAlVIli/[ERMILLS xlanjagelen-Manhattan, Kans., 'assigner to Kans.

viking Manufacturing cmpany, Manhattan,

nisieatibnouiy 2s, 195o,seriai-Nawacas let from the mill withoutreversing or changing the direction of the 'flow as itipa'ss'es throughYthe screen.

Third, to provide a screen for-a 4hammer mill having openingstherethrough for controlling the size of the material to be passed fromthe "mill 'Other objects and advantages "relating to Idetails Vof myscreen 'will beapparent froi'na 'consideration of Ythe followingL('iescl'liti'on and claims. v

The drawings, 'o'f which 'there "is one "s'h'eet, illustrate two highly-practicaliorms of my screen. Fig. 1 is a side elevational 'view of ahammer mill partially broken away'in vertical cross secftio'n toillustrate the position f-im`y screenthere- Fig. 2 is a fragmentarycross sectional view transversely through the mill and screen takenalong the plane of the line 2-2 in Fig. 1.

Fig. 3 is a perspective view of a iirst form of my screen.

Fig. 4 is a fragmentary perspective View of a second form of my screen.l

Fig. 5 is an enlarged detailed elevational v1ew of the first form of myscreen in developed or at position. Y

Fig. 6 is a fragmentary cross sectional View through the rst form ofscreen taken along the plane of the line 6 6 in Fig. 5. Y

In the drawings I have illustrated a hammer mill which comprises a lowerhousing l and an upper arcuate housing 2. A horizontal framework 3carried by the lower housing supports a driving wheel or pulley 4 andthe rotor 5 which is positioned within the housings I and 2. Asemicylindrical wall 6 completes the cylinder of the arcuate upperhousing 2 within the lower housing. The rotor 5 includes a pair ofrotatable discs having the pivot pins I extending therebetween at spacedpoints around the periphery of the discs. The pins 'I constitutepivotalsupports z'oiaims (orari-ss) land at the Sametime permitting direct flowof lthe material 'through all portionsof theisci'e'e'n.

for the bar-like hammers V8 so that -as `the rotor is driven atrelatively high speed the hammers are thrown outwardly Icy centrifugal4force to grind or beat ygrain or other material against the innercylindrical sides of theA housing. Material to be ground is deliveredinto the upper housing 2 through a feed opening -9 Yand the front discis provided `with one or more segmental openings Il) through ywhich uthematerial enters the interior of the rotor.

The leading quadrant of the upper housing 2 where the 'beaters :enterthe upper Ehousing is vextended tangentially and radially outwardly in-an outlet throat lII I and a delivery stack or -conduit I2 issecuredtotheopen l'endof the throat II. An arcuatefsc'reen I3 fis.positioned across the -inner endofsthethroat `II to coact with thehammers 3 while permitting `the vdischarge -of the ground material`-trom the housing 2 to ythe throat.

The foregoing `'construction is generally familiar in the hammer millart and is 'described in general terms only to illustrate the .positionand function of my improved screen. It should be understood that iavblast of airis l'directed linto the housinggsl and 33 to -ca'rry the.ground vmaterial lthrollgh 'the Screen land out the dllCt I2.

This vblast of aire-may fhe created? by an externally -mounted anddriven Vblower or Fmay consist :of

vanes or blades carried directly by the rotr '5 radially inwardly of thehammers 8.

It Will be noted that the throat II at its outer side extends generallytangentially with respect to the lower end of the arcuate screen I3. Asthe upperV end of the screen is curved inwardly across the top of therotor the direction of air travel from within the rotor to the throat IIapproaches and becomes generally radial with respect to the rotor andscreen. I have noted that hammer mill screens have a tendency to becomeclogged at the lower outside ends thereof with a resulting loss ofcapacity and efciency in the mill. I have further observed that thisclogging of the lower portion of the screen apparently is due to thefact that the blast of air and entrained ground material leaving therotor tangentially near the lower end of the screen must rst make aoutward turn to pass radially through the screen and then make another90 turn to pass upwardly through the outer side of the throat II.

My improved form of screen I3 is formed to provide a plurality ofslot-like openings extending circumferentially of the screen along thelower outside end thereof. The width of these.

screen there is little tendency for the slots to become clogged as wouldradially formed holes at the same position.

The rst form of my screen illustrated in Figs. 3 and 5 to 6 consists ofan arcuate plate I5 having a, multiplicity of radially formed holes orbores I4 therethrough. Toward the lower end of the screen the severalholes I4 are connected by -forming the vertical cuts or slots I6 betweenadjacent vertically aligned holes. The slots I6 are vertically separatedby unslotted portions I'I to retain the rigidity in the screen. Itshould be noted that the slots I6 are narrower than the diameter of .theholes I4 so that there is little tendency for material to pass throughthe slots in any coarser size than would pass through the holes I4themselves.

The modied form of screen illustrated in Fig. 4 consists of an arcuatescreen plate I5A having the same screen holes I4 formed Ithrough theupper end thereof and continued downwardly toward the lower end to apoint where the air iiow from the housing tends to become tangentialwith respect to the screen. At this point in the lower end of the screenthere is formed a series of transversely spaced circumferentiallyelongated arcuate slots ISA which function in the same manner as theslots I6 in the rst form of screen.

Not only does my improved .type of screen have better noncloggingcharacteristics than the old screen but it is less diiiicult andexpensive to form than the old screen as it is no longer necessary to soaccurately control the spacing of the holes through the lower end of thescreen. The width of the slots and holes is still controlled and variedin different screens to regulate the size of the ground material whichwill be discharged from the mill but it is no longer necessary tocarefully determine the spacing of the several holes I4.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. In combination with a hammer mill having a delivery throat extendingfrom a quadrant of .the hammer mill cylinder, said throat openingtangentially from one edge of said cylinder and extending across saidquadrant to open radially of the cylinder at the opposite edge of thethroat, a screen extending across said throat, said screen comprising anarcuate strip of metal having a multiplicity of circular passagestherethrough and distributed thereoverv in circumferential lines,adjacent passages near the tangential side of said throat being joinedby circumferentially extending slots narrower than the diameter of saidpassages.

2. In combination with a hammer mill having a delivery throat extendingfrom a segment of the hammer mill cylinder, said throat openingtangentially from one edge of said cylinder and extending across saidsegment to open generally radially of the cylinder at the opposite edgeof the throat, a screen extending across said throat, said screencomprising an arcuate strip of metal having a multiplicity of circularpassages therethrough and distributed thereover in circumferentiallines, adjacent passages near the tangential side of said throat beingjoined by circumferentially extending slots.

EVAN L. COLE.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date Re. 21,523 Elderkin Aug. 6, 19401,185,620 Blum June 6, 1916 1,698,758 Knittel Jan. 15, 1927 1,973,074Howes Sept. 11, 1934 2,049,808 Hunnicutt Aug. 4, 1936 2,279,219 BakerApr. 7, 1942 2,420,966 Molz May 20, 1947 FOREIGN PATENTS Number CountryDate 2,204 Germany of 1878 19,449 Austria Mar. 10, 1905

